The present invention relates to the field of data storage and retrieval. More particularly, it relates to improvements in apparatus for facilitating the handling and transport of relatively delicate data storage disks, in particular optical disks.
Owing to their intrinsic nature, it is at least highly desirable that the recording surfaces of an optical disk be protected from physical contact during handling, transport and use. Because of the immense data packing density, even a tiny scratch or mark on the disk can mean the loss of kilobytes of information. Accordingly, it is common practice to dispose an optical disk in a so-called disk "carrier" which functions to support a disk only at its periphery and provide a means for handling the disk without touching its recording surfaces. Such carriers typically comprise a generally rectangular frame having a circular aperture for receiving a disk, and means spaced about such aperture for supporting a received disk at its periphery. Optical disk carriers of this type are disclosed, for example, in U.S. Pat. No. 4,481,617, and in the commonly assigned U.S. application Ser. No. 923,509, entitled "Carrier for Data Storage Disk", filed on Oct. 27, 1986 in the names of D. J. Stark et al.
In the optical disk-carriers of the prior art, the disk is supported by a plurality of rigid tabs and/or latches spaced about the carrier aperture. These tabs and latches contacts the disk periphery only over a relatively short arc length (e.g. a few degrees) and are selectively movable toward and away from the disk periphery to capture and release a disk, respectively. Because of the relatively short arc length over which each of these tabs and latches engages the disk periphery, the carrier/disk assembly tends to be somewhat flexible and, under certain circumstances, this flexibility can lead to transport problems, for example, in automated disk-handling equipment. Moreover, for the same reason, the disk can, under certain circumstances, become separated from the carrier.
In the commonly assigned U.S. application Ser. No. 208,190 entitled "Split Carrier for Data Storage Disks" filed concurrently herewith in the names of Roger Covington et al, there is disclosed a disk-carrier which alleviates the above-noted disadvantages of the prior art carriers. Such a disk carrier comprises a pair of identical crescent-shaped frame members which are slidably coupled to define a generally circular aperture for receiving an optical disk or the like. The aperture-defining arcuate surfaces of the frame members are provided with a continuous groove which serves to engage a disk perimeter over a major arc length (e.g. more than 200 degrees). By this arrangement, the disk/carrier assembly is substantially less susceptible to premature release of the disk. This carrier has been referred to as a "split" carrier in that it is composed of two frame members which split apart to receive and release a disk.
In the split carrier referred to above, a pair of springs urge the frame members together and, of course, towards engagement with the disk perimeter. The frame members are made of a hard plastic or the like which is highly transmissive of shock waves. Thus, in the event the carrier frame is subjected to an impulse spike, as may be the case should the carrier/disk assembly fall onto the floor from a table top, such impulse will be transmitted, substantially unattended, to the retained disk. If large enough, impulses of this type can produce performance degradation in certain types of optical disk structures, particularly those in which the optical disk's recording layers are protected by closely spaced, transparent cover sheets.